header{
    width: 100%;
    height: 40px;
    background: dodgerblue;
    font-size: 30px;
    text-align: center;
    color: white;
    padding:10px 0;
}
nav{
    width: 100%;
    height: 30px;
    background: mediumblue;
    display: flex;
    justify-content: center;
    margin-top: 10px;
}
nav>a{
    width: 100px;
    height: 30px;
    line-height: 30px;;
    color: white;
    margin: 0 20px;
    text-align: center;
}